Less Sleep May Predict Heart Risk in Elderly

Action Points

Explain to interested patients that shorter sleep duration coupled with a rise in overnight blood pressure was found to increase the risk of cardiovascular disease.

TOCHIGI, Japan, Nov. 10 -- Sleeping fewer than seven-and-a-half hours each night could increase the risk of heart disease for older patients, according to researchers here.

Short sleep duration was associated with a 1.68-fold increased risk of cardiovascular disease (95% CI 1.06 to 2.66, P=0.03) in older Japanese patients with hypertension, Kazuo Eguchi, M.D., Ph.D., of Jichi Medical University, and colleagues reported in the Nov. 10 issue of Archives of Internal Medicine.

And a combination of little sleep and elevated overnight blood pressure was associated with an increased risk as well.

"Shorter duration of nighttime sleep is a predictor of incident cardiovascular disease in elderly individuals with hypertension, particularly when it co-occurs with a riser pattern of nocturnal blood pressure," the researchers said.

Lack of sleep has been associated with multiple health disorders, including obesity, diabetes, and cardiovascular disease, and has been shown to be a risk factor for all-cause mortality and coronary heart disease in epidemiological studies.

Many of these studies, however, were conducted in younger patients and in women, and did not assess the role of nighttime ambulatory blood pressure (ABP) as a risk factor for cardiovascular disease.

Patients whose blood pressure does not decrease overnight have also been reported to be at increased risk for cardiovascular disease -- especially for those whose blood pressure rises at night, which is often referred to as a "riser pattern."

So to assess whether short duration of sleep in older patients is associated with future cardiovascular disease, and whether the association is moderated by the circadian blood pressure pattern, the researchers analyzed the sleep of 1,255 patients with hypertension (average age 70.4) and followed them for an average of 50 months.

There were 476 men and 779 women, and 94% of subjects had hypertension.

During follow-up, 99 cardiovascular events occurred.

The incidence of cardiovascular disease among those who got fewer than 7.5 hours of sleep a night was 2.4 per 100 person-years, compared with 1.8 per 100 person-years in those who slept longer.

"Perhaps these older people had their sleep duration shortened by other processes such as depression or nocturia," the researchers said. "Both these conditions may shorten sleep duration and adversely affect cardiovascular outcome."

A tendency toward a synergistic interaction was observed between short sleep duration and the "riser pattern" (P=0.09).

Patients who slept less and had a "riser pattern" -- an overnight increase in blood pressure -- had a 4.43-fold increased risk of cardiovascular disease (95% CI 2.09 to 9.39, P<0.001) compared with those with longer sleep duration and no riser pattern.

Similarly, this group had the highest incidence of cardiovascular disease, but in those whose blood pressure did not rise overnight, disease incidence was similar whether they had shorter or longer sleep duration.

"It is clear that the group at greatest risk comprises those who have riser patterns and shorter duration of sleep," the researchers wrote.

They added that physicians "should inquire about sleep duration in the risk assessment of patients with hypertension."

The researchers noted several limitations to the study, including the fact that because of the limited number of patients with the riser pattern, the study was underpowered to detect an interaction at the P<0.05 level and as most of the subjects were elderly, the results may not be applicable to younger populations.

The study was supported in part by grants-in-aid from the Foundation for the Development of the Community in Tochigi, Japan; the Banyu Fellowship Program, sponsored by Banyu Life Science Foundation International; and the National Heart, Lung, and Blood Institute.

The authors reported no disclosures.

Reviewed by Zalman S. Agus, MD Emeritus Professor University of Pennsylvania School of Medicine